after one week of listening sessions, the overall sound impression is very nice. The F5 has no hum, no turn on thumb and is dead quite.
I think i like it even more than my tube amps. DC stays at around 5mv and is pretty stable. I can encourage everybody to build this great amp. Thanks to Nelson for bringing again a fantastic design to everybody. This amp will for sure stay a long time.

I have run with a tube pre, with the B1 and with an Aleph P as preamp. I'm a little bis dissapointed with the B1 / F5 combination.
gain is not issue, but the B1 sounds a little bit lean and the voices are not what i like. The Aleph P is clearly better in my setup with the F5 the overall sound is smooth as silk with a better tonal balance.
I still need to try the UGS F5 combination.

The power supply of the tested amplifier is +/-24 volts and should be rated at 6 amps continuous duty, and more than 10 amps peak per channel. Ordinary unregulated supplies will work fine, and if you need suggestions the Zen Variations #5 (AudioXpress, October 2003) and Zen Variations #3 (AudioXpress, August 2002) both have good
examples of regulators and the raw supplies that feed them. I recommend rail voltages from 23 to 25 volts.